Reprinted by self permission from thealpb(dot)com originally posted Jan. 2016
Some are naturally disappointed by the 1/10th Watt of power allowed for legal Part 15 radio transmission, or, by the same token, equally downcast about the 3-meter antenna limit.But my experience tells me the 100mW 3-meter figures were very intelligently calculated by the FCC as the right signal level to allow for compliance with 15.219.Consider these observations and tell me if you don't agree...About 6-feet from the metal window frame serving as the antenna for an AMT5000 transmitter is a Panasonic table radio tuned to that transmitter. The radio is very sensitive and extremely useful for DXing far away AM stations.But with the AMT5000 set at exactly 100mW, the antenna length measured to a precise 3-meters, the radio is over-saturated and the audio sounds like it's coming from under water.The FCC obviously calculated this delicate relationship, and with the further recognition that most Part 15 users are living near other households, any more power and Part 15 stations would be jamming their nearby neighbor's radios leading to a steep rise in complaints.On the other side of the coin the Part 15 rule for FM, 15.239, is set ridiculously low without any obvious rationation, virtually guaranteeing violation of anyone trying to make use of the FM band for low power operation.